Anderson plugs

[mickbro]

Hi all
planning a dual battery installation, will have Anderson plug for caravan fridge and also Anderson plug in rear of paj for a Engel or similar fridge.
My question is can I run a 6b&s to back of vehicle and connect 2 Anderson plugs or should I run separate cables for each Anderson?
Thanks

[nj swb]

In an ideal world, two separate cables on two separate fuses, to reduce the risk of one fault cutting power to both fridges - pulling up at the end of the day with no cold beer would be disastrous.

In reality, if they're both small compressor fridges, a single 6 B&S cable should suffice.

If you're planning to add a "house battery" to the caravan, and want to use the van Anderson to also charge that, I would use larger than 6B&S, to reduce voltage drop - but that's largely a personal opinion.

If the van fridge is a three-way (gas / 240V / 12V), that is likely to draw significantly more current on 12V, so I would recommend a dedicated 6B&S (or larger) for that circuit.

[mickbro]

Thanks nj sub yeah fair comment it is a 3way fridge so I'll just run 2 supplies

[OldEmmGee]

I would run a single cable to the rear (fused at around 50A at the battery connection) and then split to two andersons each protected by an in-line fuse at around 20A; saves on wiring and maintain independant protetction!

[Dicko1]

I would run a single cable to the rear (fused at around 50A at the battery connection) and then split to two andersons each protected by an in-line fuse at around 20A; saves on wiring and maintain independant protetction!

Yep...keep it simple but safe. I actually run 2 x 40 amp dcdc units from one cab,e , from start battery to rear tub and then to camper...no problems at all.Fuse everything.

[mickbro]

Thanks for the replies there's a couple of options to consider

[2bad4u]

I would run a single cable to the rear (fused at around 50A at the battery connection) and then split to two andersons each protected by an in-line fuse at around 20A; saves on wiring and maintain independant protetction!

This is what I have done. One plug is for the caravan and the other plug can be used to plug in my compressor, camp lights, a set of portable solar panels, etc in any combination. I also have a separate (lighter) cable run to the rear exclusively for the fridge.

[Valiant81]

Hi all; I have been caught out with chinese Anderson plugs that have flooded the market and cause me a lot of grief, time and more money. Uses the proper certified Anderson plugs and 1/2 decent heavy wire.

[Jasonmc73]

I've ran a 4 B&S length of Pajero for camper trailer, which is a Redarc BCDC1240 40Amp charger & have 120 AMp genuine anderson at the towbar.
I now know Anderson plugs are not like automoive wire & a 50 Amp Anderson is plenty to hold full 40 amps.

Off this 4B&S i have T off & 6B&S or 8B&S can't remember whilst i had it apart for when i fit TJM compreeosr unit, all fused Via a 80 Amp circuit breaker
Any new wires & my Tow Pro elite run from unfused side of the breaker & only One wire runs to my battery, neat & tidy.
But in my instance, how often am I going to use compressor at a time when BCDC is pulling full 40 amps , my hunch is hardly ever, worse thing that'll happen is it will trip the circuit breaker as they derate due to heat under bonnet i think?

In any instance i'm not concerned, when i wired trailer, i fitted a kill switch, isolator, switch off trailer if required, no biggie.

Compressor max about 36ampsish
Redarc BCDC 40 Amps max

4 B&S was the correct size cable for my application, runs from vehicle battery to BCDC1240, 10 metreish length by time it gets to camper trailer batteries & charger

It's earthed to the 3rd seat bracket, the bolt at front of bracket on the inside, it's out of the way, anodised looking bolt & bracket.

Your fridge in back of vehicle will use bugger all in my opinion.

Just work out voltage drop over distance & how much power you'll pull

You may find some interesting reading on this link below,

Personally i like Tycab wire, some wire & terminals i've seen are just crap, Chinese junk.

https://www.fridge-and-solar.net/dual_bat.htm

[nj swb]

https://www.fridge-and-solar.net/dual_bat.htm

Personally, I don't have anything against Val Rigoli, he generally writes well and provides useful information - unlike some other internet-infesters, who don't understand what they're writing, misquote information out of context and create enduring internet myths that just won't die...

But I digress.

In the linked article, Val advocates minimum of 6 B&S (aka 6 AWG, or 6 gauge) for wiring, and using 100 A fuses for short circuit protection. Short circuit protection is a good idea, fuses at all batteries are absolutely essential.

Fuses should also be used for overload protection, to protect a cable against overheating from long-term overload. If the cable insulation is allowed to get too hot it can soften and deform, to the point that it no longer insulates as intended. Which is when that short circuit protection is most likely to be required.

So a cable's current rating is determined by the maximum safe temperature for its insulation - which is related to the properties of the insulating material, and the ambient temperature around the cable.

So, what is 6 B&S cable rated to carry? Good luck figuring that out!

A quick google of 6 B&S cable came up with some worrying results:

Sparesbox here are advertising a Narva 6 B&S twin as 140 A.

Perhaps it has fancy insulation?

Narva's product page for the cable also proclaims it to be 140 A rated, using "oxygen free copper and RoHS compliant polyvinyl-chloride." No information on a temperature rating for the PVC.

Tycab specify their PVC insulation is 90 degree rated (that's the "V90" bit), as does Tinker. Tycab rate their cable at 103 A, and Tinker call theirs 100 A.



Jaydee Auto get a gold star!
Gold star.jpeg

https://jaydeeautocables.com.au/prod...le-single-core

SPECIFICATIONS

AMP Rating at 30°C: 103amp (JASO D609 derating factors apply)

Tycab Code: ABC111203

Nearest AWG: 6

Strand #/Size: 168/0.32

Nominal Area: 13.5mm²

Insulation Thickness: 1.1mm

Electrical Resistance at 20°C: 1.4ohm/km

Nominal O.D.: 7.2mm

Mass (kg/100m): 15.6

Conductor: OXYGEN FREE Plain Copper Wire to AS/NZS 1125

Insulation: V90 degrees Celsius PVC to AS/NZS 3808


DERATING FACTORS


Derating Factors for Bundling of Single Core Cables per JASO D609
As the number of cables bundled together increases, the current capacity of each cable in the bundle decreases as per the following chart.
Cable Bundle Qty = Derating Factor for 6 B&S

• 1 x Cable = 100% capacity (103amp)
• 2 x Cables = 80% capacity (82amp)
• 3 x Cables = 70% capacity (72amp)
• 4 x Cables = 60% capacity (62amp)
• 5 x Cables = 55% capacity (57amp)
• 6 x Cables = 50% capacity (52amp)
• 7 x Cables = 50% capacity (52amp)

Derating Factors for Ambient Temperatures °C per JASO D609
As the ambient temperature increases, the current capacity of the cable decreases as per the following chart.
Ambient Temperature °C = Derating Factor for 6 B&S

• 30°C = 100% capacity (103amp)
• 40°C = 90% capacity (93amp)
• 50°C = 76% capacity (78amp)
• 60°C = 60% capacity (62amp)
• 70°C = 45% capacity (46amp)

I recall slogging across the Simpson Desert with the dash displaying an ambient temperature in the mid 40s. I like to rate my cables for at least a 50 degree ambient, which brings the cable rating back to 78 A - that's the JayDee's Tycab cable, with V90 insulation. What's the insulation temperature rating for the cable installed in your 4wd?

Jaycar sell a twin core 6 gauge cable for which they specify a maximum temperature of 80 degrees, and a rating of 80 A or 90 A, depending on which page you look at. That won't be rated to 78 Amps in the Simpson Desert.

But what about the temperature derating of the fuse? As it gets hot, it will derate along with the cable, so the cable will still be protected.

Maybe.

In the linked article above, Val advocates "Mega" fuses - fair enough, they're nice fuses.

Littelfuse designed and patented "Mega" fuses, and their datasheet can be found here.

Val's recommended 100 A fuse is rated by Littelfuse to protect 16mm2 cable - 6 gauge is smaller than that (nominally 13.5mm2).

Littelfuse's datasheet also contains a table titled "max. allowed current load [A] at ambient temperature"

Littelfuse Mega fuse.png

By that table, a 100 A fuse under a bonnet is good for less than 90 A, but is till good for 76 A at 65 degrees ambient. I don't believe it will be adequately protecting too many 6 gauge cables in a 4wd.

So, what does all this mean (not that anybody has read this far... )?

If you're installing 6 gauge cable, make sure you understand its current rating, and don't believe that it's adequately protected by a 100 A fuse.

If you want to use a 100 A fuse on your circuit, use larger than 6 gauge cable - and make sure you understand its current rating.

[Jasonmc73]

I think it's great idea to have big fat fuse at EACH battery if joining two together as per his diagrams.
(I have no 100 amp fuses, mine are actually 80amp)

I also believe the "Amp rating" of a cable in DC current is the MELTING POINT, not what it can carry all day long.

Personally i believe if you have a dead short, cable rubs through on the body, not a bad idea to have a good size fuse that will go pop, exactly how i have wired mine, sort of , but it is through an 80amp circuit breaker at vehicle & see this link, this is my junction box in my trailer.

https://www.solidkit.com.au/product/...fuse-junction/

Bit hard to explain

But the side with three terminals, that is where main 4 B&S from vehicle goes to, meets up with BCDC & one big fat wire to trailer on/off switch & onto a blue sea fuse block with blade fuses, suitable sizes for auxillaries & wires running of that.

The side of this block with one wire goes to camper batteries, neat & tidy, not required, but it's water proof acts as junction box & fuses between everything onto auxillary fuses & main trailer switch.

All the midi fuses 80amp & 80amp circuit breaker i fitted in vehicle are doing is protecting me from fire, in the event of a dead short, it's a big cable, capable of big heat.
I have no idea whom he is, but i double checked his info & learnt a bit, reckon he's no dill myself, chose my own path & set sail .
Also Redarc have useful info.

Few articles on is little site, here's one about voltage drop & cables, few figures useful in practical world.

https://www.fridge-and-solar.net/wire.html